Effects of Vasopressors on Immune Response

Rationale:

Septic shock is a major medical challenge associated with a high mortality rate and increasing incidence. It has become clear that the majority of septic patients do not succumb to an initial pro-inflammatory "hit", but at a later time-point in a pronounced immunosuppressive state, so called 'immunoparalysis'. Noradrenaline is a catecholamine and the cornerstone treatment for the improvement of hemodynamic parameters in septic shock. However, catecholamines exert profound immunomodulatory effects which have mainly been studied for adrenaline. It profoundly inhibits LPS-induced production of TNF-α, and enhances production of anti-inflammatory IL-10 in vitro, as well as in animal and human models of inflammation. Although in vitro studies have shown that noradrenaline inhibits LPS-induced pro-inflammatory cytokine production as potently as adrenaline, the effects of noradrenaline on the immune system in vivo have not yet been studied. Furthermore, effects on the immune system of viable vasopressor alternatives for the treatment of septic patients, namely phenylephrine and vasopressin, need to be established in humans in vivo.

Objective: To investigate whether noradrenaline exerts immunomodulatory effects in humans in vivo and to compare noradrenaline to other vasopressors (phenylephrine and vasopressin).

Study design: A randomized double-blind placebo-controlled study in healthy human volunteers during experimental endotoxemia.

Study population: 40 healthy male volunteers, aged 18-35 yrs.

Intervention:

• The noradrenaline group (n= 10): subjects that will receive intravenous infusion of noradrenaline 0.05 μg/kg/min for 5 hours, starting 60 minutes before intravenous administration of 2 ng/kg LPS.
• The phenylephrine group (n=10): subjects that will receive intravenous infusion of phenylephrine 0.5 μg/kg/min for 5 hours, starting 60 minutes before intravenous administration of 2 ng/kg LPS. .
• The vasopressin group (n = 10): subjects that will receive intravenous infusion of vasopressin 0.04 IU/min for 5 hours, starting 60 minutes before intravenous administration of 2 ng/kg LPS.
• The placebo group (n = 10): subjects that will receive intravenous infusion of NaCl 0.9% for 5 hours, starting 60 minutes before intravenous administration of 2 ng/kg LPS.

Main parameters/endpoints:

The difference of LPS-induced TNF-α plasma concentrations following endotoxemia between the noradrenaline and the placebo groups

Inclusion criteria

• Written informed consent
• Age ≥18 and ≤35 yrs
• Male
• Healthy

Exclusion criteria

• Use of any medication
• Smoking
• Previous spontaneous vagal collapse
• History of atrial or ventricular arrhythmia
• (Family) history of myocardial infarction or stroke under the age of 65 years
• Cardiac conduction abnormalities on the ECG consisting of a 2nd degree atrioventricular block or a complex bundle branch block
• Hypertension (defined as RR systolic > 160 or RR diastolic > 90)
• Hypotension (defined as RR systolic < 100 or RR diastolic < 50)
• Renal impairment (defined as plasma creatinin >120 μmol/l)
• Liver enzyme abnormalities
• Medical history of any disease associated with immune deficiency
• CRP > 20 mg/L, WBC > 12x109/L, or clinically significant acute illness, including infections, within 4 weeks before endotoxin administration
• Participation in a drug trial or donation of blood 3 months prior to the LPS challenge
• Use of recreational drugs within 7 days prior to experiment day
• Recent hospital admission or surgery with general anaesthesia (<3 months)
• Known anaphylaxis or hypersensitivity to the study drugs or their excipients
• Recent anaesthesia with halogenated agents
• Known cardiovascular disease (coronary artery disease)
• Known chronic nephritis